More high-powered law firms have joined nursing homes and other health care providers in the fight over whether the facilities, faced with COVID-19 wrongful death lawsuits, have liability protections.

Providers accused of causing deaths through lax COVID-19 provisions say the litigation belongs in federal court and argue they have immunity under the federal Public Readiness and Emergency Preparedness Act. The 2005 act protects certain entities from lawsuits related to the administration or use of “countermeasures,” like drugs, products and devices, during a public health emergency.